It seems strange to me that after the Uno, FIAT used trailing arms in the Tipo, the Punto, the Brava/Bravo, and the Coupe. And then, for some reason, switched back to torsion beam for the Mk2 Punto and the larger Stilo. I would have thought that the unsprung weight and lack of independance would have hurt the ride quality. (Yet, for some reason, the Mk1 Punto ended up with an awful ride).
The best FWD rear suspension in MY opinion is the 'Type 4' setup in the Croma (old), Thema, Alfa 164, Saab 9000. Multilink - McPherson strut, knife-edge fore-and-aft location arms, and four slender tie-rods (about 2cm diameter) under the car, the rods being as long as possible with the pivot points bolted to a subframe across the car's centreline (for minimal geometry change). This arrangement gives near-perfect geometry with no change laden/unladen and no bobbing up and down when using the handbrake on a hill start, and low unsprung weight/long travel McPherson struts for excellent ride quality. Only drawback was space requirement (rear strut turrets inside boot) and cost. Hydropneumatic ride height control was even an option...